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UndermineBriarEverglade
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Yeah it's kind of a kludge, the charge pump uses a few mA in steady state without a disable. It would be better to use a LTC1044 or something but I
wanted to test it without waiting for new components to arrive.
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UndermineBriarEverglade
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Charge pump works well to trigger relay and safety mechanisms are adequate. But the HV converter is just whalloping this 9V battery. 2-4V most of the
time and ringing to 14V, enough to brown out the microcontroller once it starts charging up the cap. I should have scoped this in the early design
phase, I just assumed the source was sufficient based on the output voltage. Even lithium batteries droop too much. I'll need to use a separate
battery (like Sir_Gawain) or redesign to feed the small circuitry with a boost-buck converter or some nonsense.
I'll do my ETN synth soon. Why does it have to be so difficult to get nitrate salts, ammonia, nitric acid when you can literally buy POUNDS of arsenic
trioxide online.
[Edited on 2024-7-25 by UndermineBriarEverglade]
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UndermineBriarEverglade
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Sir_Gawain, what quantity of ETN are you able to detonate unconfined with your EBW setup? Mine failed to detonate 50mg of loose ETN. I can test
initial voltage, but without a way to measure discharge time or current I can't tell if the wire is actually exploding or just melting faster than a
camera frame.
Also, based on a candle flame below aluminum foil, I do think a nichrome coil around an ETN cap might be a simpler detonator. Maybe with a little
motor to vibrate it.
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Sir_Gawain
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Location: Due South of Due West
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Mood: Way less sad
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Quote: Originally posted by UndermineBriarEverglade  | Sir_Gawain, what quantity of ETN are you able to detonate unconfined with your EBW setup? Mine failed to detonate 50mg of loose ETN. I can test
initial voltage, but without a way to measure discharge time or current I can't tell if the wire is actually exploding or just melting faster than a
camera frame.
Also, based on a candle flame below aluminum foil, I do think a nichrome coil around an ETN cap might be a simpler detonator. Maybe with a little
motor to vibrate it. |
While testing, I would add some ETN (<100mg) to a piece of tape, add the bridge wire, and fold the tape over. These little detonators were quite
powerful and always fully detonated. 500mg wrapped in tape blew a sizable hole in a steel can.
It’s pretty easy to tell if the wire is exploding properly or just rapidly melting. Set off a bridge wire (about 5 mm long) in air. It should make a
loud crack and produce a brief blinding flash. It should also leave a film of vaporized copper on nearby surfaces.
One of the biggest problems with the cook-off type detonator is the tendency to simply catch fire, possibly igniting the main charge. I’ve had it
happen to me before, and trust me, a slowly smoldering stick of dynamite is not a fun thing.
“Alchemy is trying to turn things yellow; chemistry is trying to avoid things turning yellow.” -Tom deP.
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UndermineBriarEverglade
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It does make a loud crack, brief flash, and metal dust deposits. In slow-motion video I get one frame of complete white and then a spray of sparks.
Hmm, that's a good point.
edit: Successful detonation with a slightly larger amount of ETN in tape. Installed new relay after finding the previous one was stuck closed. Contact
resistance might have been increased in previous attempts, explaining weak bursts. Maybe I will "flicker" the relay after firing to try and shake off
any hot gunk. Reed relays might not be the way to go. Must have been <10 bursts before it died.
[Edited on 2024-8-9 by UndermineBriarEverglade]
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